1. Field of the Invention
The invention relates to a sensing method and more particularly relates to a sensing method of optical touch.
2. Description of Related Art
Due to the convenient and highly-intuitive operation, touch electronic products are popular among the consumers and gradually become the main trend of the market in recent years. Among resistive, capacitive, and back projection touch screens that have been used for some time, the capacitive touch screen has the best touch performance but it is also the most expensive one. The production costs of the capacitive touch screen increase with its screen size, thus limiting the application. Optical touch technology that utilizes an optical sensing module to detect the touched position has been proposed as an alternative to the capacitive touch screen. The optical touch technology has advantages, such as low cost and good accuracy, etc., which is more competitive in the market. It thus has also become another option for large-sized touch screens.
Generally speaking, the way the optical touch technology performs sensing is through disposing a reflector and an optical sensing module on the edge of the screen, and causing the light provided by a light source being reflected by the reflector and transmitted to the optical sensing module. When a touch object is above the display surface and blocks a portion of the light reflected by the reflector, a shadow is formed on the optical sensing module, by which the position of the touch object is calculated.
However, for a large-sized touch screen, it is difficult to maintain the optical sensing module and the reflector on the same plane. Therefore, deformation of the touch plane may occur and influence the reflective efficiency of the reflector or even make it difficult to transmit the light provided by the light source through the reflector and to form the shadow on the optical sensing module. As a result, determination of the touch point is affected.
In order to overcome the difficulty in determining the touch point due to the deformation of the touch plane, an optical sensing module having an image sensing array is provided for receiving light that enters the optical sensing module within an incident angle range. Therefore, when the touch plane is deformed, different incident angles are selected for different sensing pixels of the optical sensing module to achieve stronger light intensity, so as to obtain better reflection signals for determining the touch point. However, the sensing method used by the current optical touch technology requires analysis on each sensing pixel of the optical sensing module in order to obtain the incident angles of stronger light intensity for determining the touch point, which takes much time.